1. Field of the Inventions
The inventions relate to an electrically controlled pressure regulator, which comprises an actuator in the form of a solenoid primarily intended to determine the pressure in a damping medium flow between the damping chambers of a shock absorber.
2. Description of the Related Art
A known design within the field of the inventions is described by patent SE531108 of the Applicant, in which the closing actuating force of a pilot stage in a shock absorber valve is determined by the force from an electrically controlled solenoid.
In this patent application, a valve/pressure regulator is described in the form of a pilot-controlled two-stage valve, intended to control a damping medium flow between the two damping chambers of a hydraulic shock absorber. The shock absorber valve comprises a valve housing having at least one main valve with a movable valve part in the form of a main cone disposed between a main valve spring arrangement and a seat, as well as a pilot valve comprising a pilot slide. The main cone delimits a pilot chamber in the valve housing, in which the valve main spring and the pilot slide are disposed. The characteristics of the shock absorber valve are primarily controlled by the pressure build-up in the pilot chamber that is adjusted by the position of the pilot slide in the pilot chamber. The position is determined by the force balance between the spring force of a pilot spring and the counter actuating force from an electrically controlled solenoid, but also by the feedback pressure opening force created by the pressure in the pilot chamber. Energization of the solenoid adjusts the position of a driver or a solenoid armature having a solenoid armature rod disposed inside a solenoid chamber in the solenoid. The solenoid chamber is pressurized by virtue of the fact that a longitudinal and a transverse hole run in the solenoid armature rod and connect the pilot chamber to the solenoid chamber. As a result of different diameters of the upper and lower part of the pilot slide, a certain damping of the movement of the pilot slide is created.
The pressurization of the solenoid chamber causes damping medium to flow through the solenoid that thus can become more sensitive to dirt. Precise tolerances between the solenoid armature rod and the valve housing are therefore required to enable dirt insensitivity to be attained. Precise tolerances can lead to high production costs and a certain undesirable friction.